Correction Example Of Program Errors; Fig. 21.3 Rom Correction Processing Flow - Fujitsu MB90420/5 (A) Series Hardware Manual

21.2.1 Correction Example of Program Errors

The body of the patch program and the program address are transferred to the MCU through the connector
(UART). MCU then writes that information to the EEPROM.
n When a program error occurs
Figure 21.3 shows an example of ROM correction processing when a program error occurs.
ROM
RAM
ROM CORRECTION
MB90427
FFFFFF
H
(3)
Erroneous program
(1)
Register setting for
ROM correction
Patch program
(2)
000000
H

Fig. 21.3 ROM Correction Processing Flow

External E
• Count of program byte
• Interrupt generation address
• Patch program
Data transfer via UART
21-7
2
PROM